If all the candidates are so displeasing that you really can’t vote for any of them, you can write-in someone else’s name. I don’t mean “Mickey Mouse” or anything so trivial, but somebody you admire, respect, and would like to elect.
You’ll have “wasted” your vote in some ways, but you’ll have made it meaningful in other ways. You get to make a statement about your beliefs, while not supporting some default candidate who offends you.